1. Technical Field of the Invention
The present invention relates to an integrated electronic circuit which comprises a thin layer portion based on hafnium oxide. It also relates to a process for forming such a thin layer, as well as the use of this process for realizing an integrated electronic circuit.
2. Description of Related Art
It is known to use thin layers of hafnium oxide, of the chemical formula HfO2, in the fabrication of integrated circuits, particularly for realizing portions of material with a high dielectric permittivity. But this high dielectric permittivity depends on the crystallographic structure of the hafnium oxide. In its monoclinic phase, hafnium oxide has a relative dielectric permittivity ∈r which is between 16 and 20, and this value is between 25 and 80 when the hafnium oxide has a cubic, tetragonal, or orthorhombic structure.
Currently, hafnium oxide obtained in the fabrication of integrated circuits is either monoclinic or amorphous. When it is amorphous, it later crystallizes in monoclinic form when the circuit is heated during fabrication, after the formation of the hafnium oxide portion. The relative dielectric permittivity of the hafnium oxide portion is then once again below about 20.
Hafnium oxide portions additionally containing atoms of scandium (Sc), yttrium (Y), aluminum (Al) or titanium (Ti) have also been realized in integrated circuits, in order to stabilize an amorphous phase of a mixed oxide of hafnium and one of these metals. But for these added metals, the mixed oxide material which is obtained still has an insufficient dielectric permittivity. In addition, for some of them, the mixed oxide material again crystallizes into a monoclinic structure.
The exists a need in the art for a material based on hafnium oxide, adapted for the fabrication of integrated electronic circuits and having a high dielectric permittivity.
There is also a need in the art for a material based on hafnium oxide, adapted for the realization of electrically insulating portions having very low leakage currents.